Sign up to receive free email alerts when patent applications with chosen keywords are publishedSIGN UP

Abstract:

Provided is a blast treatment method that can be implemented simply and
efficiently blast a treatment subject while preventing fragments of the
subject from scattering outward. The blast treatment method is used to
blast a treatment subject 10 having a bursting charge 12 and a shell 11,
and includes: an inside explosive disposing step of arranging an inside
explosive 20 to be used to blast the treatment subject 10 around the
treatment subject 10; an outside explosive disposing step of arranging an
outside explosive 34 having a greater detonation velocity than the inside
explosive 20 at positions on an outer side of the inside explosive 20;
and a blast step of simultaneously initiating detonation of the outside
explosive 34 at a plurality of positions spaced from each other at
predetermined intervals along a particular direction to thereby
simultaneously initiate detonations of the inside explosive 20 at a
plurality of positions along the particular direction by the detonation
of the outside explosive 34, and thereby blasting the treatment subject
in such a manner that the detonations of the inside explosive 20 are
completed before the detonation of the bursting charge 12 initiated by
the detonations of the inside explosive 20 is completed.

Claims:

1. A blast treatment method for blasting a treatment subject having a
bursting charge and a shell for housing therein the bursting charge, the
method comprising: an inside explosive disposing step of disposing an
inside explosive to be used to initiate detonation of the bursting charge
and to blast the treatment subject around the treatment subject; an
outside explosive disposing step of disposing an outside explosive having
a greater detonation velocity than the inside explosive and used to
initiate detonation of the inside explosive at positions on an outer side
of the inside explosive; and a blast step of simultaneously initiating
detonation of the outside explosive at a plurality of positions spaced
from each other at predetermined intervals along a particular direction
to thereby simultaneously initiate detonation of the inside explosive at
a plurality of positions along the particular direction by the detonation
of the outside explosive so that detonation of the bursting charge is
initiated by the detonations of the inside explosive, and thereby
blasting the treatment subject in such a manner that the detonations of
the inside explosive are completed before the detonation of the bursting
charge initiated by the detonations of the inside explosive is completed.

2. The blast treatment method according to claim 1, wherein in the blast
step, both ends of the outside explosive in the particular direction are
simultaneously initiated to thereby simultaneously start the detonation
of the inside explosive at both ends thereof in the particular direction
by the detonation of the outside explosive, and thereby propagating the
detonations of the inside explosive which respectively have started on
the both ends thereof in the particular direction so that the detonations
approach each other along the particular direction.

3. The blast treatment method according to claim 2, wherein the treatment
subject has a shape that extends in a given direction, and in the blast
step, the detonation of the outside explosive is initiated at the both
ends thereof in a longitudinal direction of the treatment subject, with
the longitudinal direction being the particular direction.

4. The blast treatment method according to claim 2, wherein the outside
explosive disposing step includes a step of arranging a plurality of
cord-like explosive members, including the outside explosive and having a
shape that extends in a direction, at positions on the outer side of the
inside explosive in parallel with the particular direction, and in the
blast step, the detonation of the outside explosive included in the
plurality of cord-like explosive members is initiated at the both ends in
the particular direction.

5. The blast treatment method according to claim 4, wherein the outside
explosive disposing step includes a step of arranging the plurality of
cord-like explosive members on an outer periphery of the inside explosive
to be equally spaced from each other.

6. The blast treatment method according to claim 2, wherein the blast
step includes a step of propagating the detonations of the outside
explosive simultaneously initiated on the both ends thereof along the
particular direction so as to approach each other along the particular
direction, and thereby making the detonations of the outside explosive
crash into each other at a position on the outer side of the inside
explosive near a center portion of the inside explosive in the particular
direction.

7. The blast treatment method according to claim 6, wherein the outside
explosive arrangement step includes a step of arranging the outside
explosive at any positions on the outer side of the inside explosive
except the center portion of the inside explosive in the particular
direction, and the blast step includes a step of making the detonations
of the outside explosive crash into each other in a region where the
outside explosive is not provided after propagating the detonations so as
to approach each other along the particular direction.

8. The blast treatment method according to claim 2, wherein In the blast
step, the both ends of the outside explosive in the particular direction
are connected to a common initiation device so that the both ends of the
outside explosive are simultaneously initiated by the common initiation
device.

9. A blast treatment device in which the blast treatment method according
to claim 1 is used to blast a treatment subject, the device comprising:
an inside explosive disposed on an outer side of a treatment subject and
used to blast the treatment subject; an outside explosive having a
greater detonation velocity than the inside explosive; and a initiation
device to be used to initiate detonation of the outside explosive,
wherein the initiation device is connected to the outside explosive so
that the outside explosive is detonated at a plurality of positions
spaced from each other at predetermined intervals along a particular
direction, the plurality of positions being such that detonations of the
inside explosive detonated by the detonations of the outside explosive
are completed earlier than the detonation of the bursting charge
initiated by the detonations of the inside explosive.

10. The blast treatment device according to claim 9, wherein both ends of
the outside explosive in the particular direction are connected to the
common initiation device.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a blast treatment method and a
blast treatment device by which an explosive subject, such as military
ammunition, is blasted to be disposed of.

BACKGROUND ART

[0002] The military ammunition (for example, artillery shells, bombs,
landmines, and underwater mines) generally has a structure where a shell
made of steel contains therein a bursting charge.

[0003] The ammunition is treated by blasting, for example. The treatment
method by blasting requires no disassembling operation. This provides
adaptability to a disposal not only of favorably preserved munitions, for
example, but also of munitions hard to disassemble because of its
deterioration over time, deformation, or the like. Further, when bombs
including chemical agents hazardous to human bodies are treated by the
treatment method, most of the chemical agents are decomposed under the
ultra-high temperature and ultra-high pressure generated by explosion. An
example of such a blast treatment method is disclosed in Patent Document
1.

[0004] According to the method disclosed in the Patent Document 1, a
treatment subject is put in a container with an ANFO explosive around it,
and the container is wrapped around by a sheet-shaped explosive having a
greater detonation velocity than the ANFO explosive. When a predetermined
end portion of the sheet-shaped explosive is initiated, the sheet-shaped
explosive progressively detonates in a given direction, and the
detonation of the sheet-shaped explosive triggers the ANFO explosive to
detonate progressively in a given direction. The detonation thereby
caused breaks the shell of the object and detonates the bursting charge
contained therein so that the object is blasted.

[0005] According to the method, the detonation vector of the ANFO
explosive filled inside of the sheet-shaped explosive is directed inward
by the detonation of the sheet-shaped explosive. When the detonation
vector of the ANFO explosive is directed inward, the detonation vector of
the bursting charge in the shell, which was originally directed outward,
is directed inward. This slows down fragments of the shell scattering
outward due to the explosion of the bursting charge.

[0006] Depending on the type or density of the bursting charge contained
in the treatment subject, the velocity of detonation propagation of the
bursting charge may be very high. If the conventional blast treatment
method described above is employed to detonate the bursting charge thus
characterized, the detonation of the bursting charge may propagates
faster than the detonation of the ANFO explosive. Then, the bursting
charge detonates before the ANFO explosive provided on its outer side
detonates, and as a result, it increases the risk of scattering the shell
fragments outward. [0007] Patent Document 1: Japanese Patent Application
Publication No. 2005-291514

SUMMARY OF THE INVENTION

[0008] To solve the technical problem, the present invention provides a
blast treatment method capable of more reliably preventing fragments of a
treatment subject, such as a shell, from scattering outward.

[0009] To achieve the object, a blast treatment method according to the
present invention is a method for blasting a treatment subject having a
bursting charge and a shell for housing therein the bursting charge, the
method including: an inside explosive disposing step of disposing an
inside explosive to be used to initiate detonation of the bursting charge
and to blast the treatment subject around the treatment subject; an
outside explosive disposing step of disposing an outside explosive having
a greater detonation velocity than the inside explosive and used to
initiate detonation of the inside explosive at positions on an outer side
of the inside explosive; and a blast step of simultaneously initiating
detonation of the outside explosive at a plurality of positions spaced
from each other at predetermined intervals along a particular direction
to thereby simultaneously initiate detonation of the inside explosive at
a plurality of positions along the particular direction by the detonation
of the outside explosive so that detonation of the bursting charge is
initiated by the detonations of the inside explosive, and thereby
blasting the treatment subject in such a manner that the detonations of
the inside explosive are completed before the detonation of the bursting
charge initiated by the detonations of the inside explosive is completed.

[0010] According to the method wherein the detonation of the outside
explosive is simultaneously initiated at the plurality of positions
thereof spaced from each other at predetermined intervals along the
particular direction so that the detonation of the inside explosive is
simultaneously triggered at the plurality of positions thereof along the
particular direction, the treatment subject is blasted in such a manner
that the detonations of the inside explosive are completed before the
detonation of the bursting charge initiated by the detonations of the
inside explosive is completed. Therefore, a detonation vector of the
inside explosive directed inward is propagated to the bursting charge not
yet detonated, which ensures that a detonation vector of the bursting
charge is directed inward. This effectively prevents fragments of the
treatment subject from scattering outward.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a sectional view showing an example of an object to be
subjected to blast treatment by a blast treatment method according to the
present invention.

[0012] FIG. 2 is a schematic perspective view showing a state where the
treatment subject shown in FIG. 1 is mounted in a blast treatment device
using the blast treatment method according to the present invention.

[0013] FIG. 3 is a longitudinal sectional view of the state shown in FIG.
2.

[0014] FIG. 4 is a cross-sectional view of the blast treatment device
illustrated in FIG. 2.

[0015] FIG. 5 is an explanatory view showing an exemplary cord-like
explosive element member used for the blast treatment device shown in
FIG. 2.

[0016] FIG. 6 is a schematic perspective view showing another embodiment
of the blast treatment device used for the blast treatment method
according to the present invention.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

[0017] Hereinafter, an embodiments of a blast treatment method according
to the present invention are described in detail referring to the
accompanied drawings. FIG. 1 is a sectional view of a conventional
munition 10 which is a treatment subject. FIG. 2 is a perspective view of
a blast treatment device to which the blast treatment method according to
the present invention is applied. FIG. 3 is a longitudinal sectional view
of the blast treatment device. FIG. 4 is a cross-sectional view of the
blast treatment device.

[0018] As illustrated in FIG. 1, the conventional munition 10 has such a
shape that axially extends. The conventional munition 10 has a shell 11
made of steel and a bursting charge 12.

[0019] Examples of a material of the bursting charge 12 are TNT and picric
acid. When the bursting charge 12 is initiated by a fuze not illustrated
in the drawings to blast, the shell 11 is broken, and fragments of the
shell 11 are scattered around.

[0020] For example, as illustrated in FIG. 2, the blast treatment method
according to the present invention is used in a blast treatment device 1
including an inside explosive 20, a plurality of cord-like explosive
members 30, a container 40, and an electric detonator (initiation device)
50.

[0021] The inside explosive 20 is used to blast the conventional munition
10. The cord-like explosive members 30 include an outside explosive 34
used to initiate detonation of the inside explosive 20. The cord-like
explosive member 30 has such a shape that extends in a direction. The
container 40 houses therein the conventional munition 10, the inside
explosive 20, and the cord-like explosive members 30. The electric
detonator 50 is used to initiate detonation of the outside explosive 34.
These structural elements will be described later in detail.

[0022] The blast treatment method includes the steps described below.

[0023] 1) Outside Explosive Disposing Step

[0024] This step is a step of disposing the outside explosive 34 at
positions on an outer side of the inside explosive 20.

[0025] The cord-like explosive members 30 used in this embodiment are
obtained from string-like detonating cord detonating cord in which a
powder core, PETN, is covered with an external cylinder 32. As
illustrated in FIG. 5, the external cylinder 32 and the outside explosive
34 made of PETN and housed inside the external cylinder 32 constitute the
cord-like explosive members 30. A material of the external cylinder 32
is, for example, plastic linearly extending in a direction. The cord-like
explosive members 30 thus structurally characterized have a detonation
velocity of approximately 6 to 7 km/s.

[0026] In this step, the long string-like detonating cord prepared in
advance is cut so as to fit the size and shape of the container 40 to
provide the plurality of cord-like explosive members 30. According to the
present exemplary embodiment, 16 cord-like explosive members 30 all
having an equal length are formed from the detonating cord.

[0027] Then, eight of the 16 cord-like explosive members 30 are provided
on an axial end of the container 40, and the other eight are provided on
the other axial end of the container 40 as illustrated in FIG. 2. The
container 40 has a substantially cylindrical shape extending in a
direction in parallel with an axial direction of the conventional
munition 10 which is a longitudinal direction thereof. Therefore, the
cord-like explosive members 30 are arranged on axial ends of the
conventional munition 10 on both sides thereof. More specifically, eight
of the 16 cord-like explosive members 30 and the other eight thereof are
arranged on an inner surface of the container 40 at the axial ends on
both sides thereof so that the eight explosive members 30, eight each,
are arranged in parallel with the axial direction of the container 40 and
equally spaced from one another. Then, the eight explosive members 30,
eight each, are bundled into one on bottom surfaces of the container 40
in the axial direction on both sides thereof so that they are
respectively bundled into one on the center axis of the container 40. The
cord-like explosive members 30 are not provided in vicinity of an axial
center portion of the container 40.

[0028] The container 40 should be able to maintain the shape of the inside
explosive 20 when the inside explosive 20 is loaded therein. The
container 40 may be shape-retainable such as a case made of hard resin,
or may be a flexible bag.

[0029] 2) Inside Explosive Disposing Step

[0030] In this step the inside explosive 20 is disposed so as to encompass
the conventional munition 10.

[0031] In this step, the conventional munition 10 is first contained in
substantially the center portion of the container 40 so that the axis
line of the conventional munition 10 and the center axis of the container
40 exactly match each other.

[0032] Then, the inside explosive 20 is poured into between the outer
surface of the conventional munition 10 and the inner surface of the
container 40 so that the conventional munition 10 is surrounded by the
inside explosive 20. The inside explosive 20 is poured into the container
40 so that the inside explosive 20 does not reach the axial bottom
surfaces of the container 40 on both sides thereof. More specifically,
there are predetermined clearances left unfilled between the axial both
ends of the inside explosive 20 and the axial both bottom surfaces of the
container 40 after the inside explosive 20 is poured into the container
40.

[0033] Though the inside explosive 20 is not particularly limited as far
as it has a lower detonation velocity than the outside explosive 34, it
is preferable to use an explosive having fluidity such as powder or
liquid. Specific examples of the explosive are emulsion explosive, slurry
explosive, and ANFO explosive. The emulsion explosive and the slurry
explosive both have a detonation velocity of approximately 5 km/s. The
ANFO explosive has a detonation velocity of approximately 3 km/s.
Therefore, the outside explosive 34 has a considerably greater detonation
velocity than the inside explosive 20.

[0034] 3) Blast Step

[0035] In this step, the outside explosive 34 included in the cord-like
explosive members 30 is initiated to thereby detonate the inside
explosive 20 so that the conventional munition 10 is blasted by a
detonation power of the inside explosive 20.

[0036] In this step, the electric detonator 50 is commonly connected to
the cord-like explosive members 30. More specifically, the electric
detonator 50 is connected to a bundle of the cord-like explosive members
30 bundled into one on each of the axial bottom surfaces of the container
40 so that all of the cord-like explosive members 30 are equally distant
from the electric detonator 50.

[0037] Next, the electric detonator 50 is connected via a firing cable 60
to a firing device not illustrated in the drawings.

[0038] Then, the firing device is manipulated. Then, the electric
detonator 50 simultaneously initiates all the outside explosive 34
included in all of the plurality of cord-like explosive members 30. The
detonation of the outside explosive 34 simultaneously starts in all of
the cord-like explosive members 30.

[0039] First, the respective detonations of the outside explosive 34 are
propagated radially outward from the center axis of the container 40 on
the axial bottom surfaces both of the container 40. The respective
detonations of the outside explosive 34 are then propagated on an outer
peripheral surface of the container 40 along a direction in parallel with
the center axis of the container 40. The detonations of the outside
explosive 34 are propagated from the axial both ends of the container 40
so as to approach each other. The detonation waves of the outside
explosive 34 thus propagated collide with one another in vicinity of the
axial center portion of the container 40, generating a high-pressure gas
in vicinity of the center portion. Thus, the center portion is the
destination where the propagated detonations end.

[0040] The detonation of the inside explosive 20 is initiated on the axial
both ends thereof by the detonation waves of the outside explosive 34
surrounding the inside explosive 20, and an detonation power of the
outside explosive 34 directed inward is applied to the inside explosive
20 at the time. Therefore, the detonation vector of the inside explosive
20 is directed inward. The inside explosive 20, while generating the
detonation waves directed inward as a result of the detonations of the
outside explosive 34, is detonated progressively from the axial both ends
toward vicinity of the axial center portion of the container 40 along the
center axis of the container 40.

[0041] When the inside explosive 20 starts to detonate, the detonation
power of the inside explosive 20 is transmitted to the conventional
munition 10 arranged inside of the inside explosive 20. The detonation
power of the inside explosive 20 compresses the shell 11 of the
conventional munition 10, and also initiates detonation of the bursting
charge 12 provided inside the conventional munition 10. The bursting
charge 12 starts to detonate at the both ends thereof in the axial
direction of the container 40.

[0042] More specifically, when the detonation waves of the inside
explosive 20 are propagated to the shell 11 and finally arrive at the
bursting charge 12, the bursting charge 12 is initiated after a short
detonation latency is over. The detonation waves of the bursting charge
12 are propagated at an increasingly higher speed along a direction
toward the center axis of the container 40. The detonations of the
bursting charge 12 initiated on the axial both ends of the container 40
and thus propagated end with colliding with the detonation waves
propagated from the other end in vicinity of the center portion of the
container 40.

[0043] The propagation of the detonations of the inside explosive 20 thus
progress from the axial both ends toward the axial center portion of the
container 40 at the same time. Therefore, a propagation time for the
detonations of the inside explosive 20 to end is, by simple arithmetic,
at most half a conventional propagation time required for the inside
explosive 20 to unidirectionally progress from one end to the other.
Thus, the detonation of the inside explosive 20 is completed in a shorter
time as compared to the related art wherein the detonation of the inside
explosive 20 starts on one end alone, propagating toward the other end.
Particularly when the detonations of the inside explosive 20 are
propagated in the axial direction of the conventional munition 10 having
such a shape that axially extends as in the present exemplary embodiment,
an amount of time necessary for detonating the inside explosive 20 is
significantly reduced.

[0044] As described above, when the detonation waves of the inside
explosive 20 finally arrive at the bursting charge 12, the bursting
charge 12 is initiated after the short initiation latency is over. The
detonation waves of the bursting charge 12 cease to be propagated in
vicinity of the center portion of the container 40 before the propagation
overly increases its speed.

[0045] Therefore, the detonation propagation of the bursting charge 12
ends before overtaking the detonation propagation of the inside explosive
20. When the bursting charge 12 is detonated, the inward detonation power
is always applied thereto from the inside explosive 20 provided around
the bursting charge 12. This directs the detonation vector of the
bursting charge 12 inward, thereby preventing the fragments of the shell
11 from scattering outward.

[0046] The cord-like explosive members 30 are not provided in vicinity of
the center portion of the container 40. Therefore, the detonation power
is not newly induced by the outside explosive 34 in vicinity of the
center portion. However, the high-pressure gas is generated in vicinity
of the center portion by the collision of the detonation waves of the
outside explosive 34 as described above. The high-pressure gas applies a
power having inward directionality to the inside explosive 20, serving to
direct the detonation vector of the inside explosive 20 inward in
vicinity of the center portion. Then, the detonation vector of the
bursting charge 12 is directed inward as well. As a result, the fragments
of the shell 11 are prevented from scattering outward in vicinity of the
center portion of the container 40.

[0047] According to the present exemplary embodiment, the cord-like
explosive members 30 including the outside explosive 34 provided on the
outer peripheral surface of the inside explosive 20 are spaced from one
another as illustrated in FIG. 2, for example. The outside explosive 34
has an adequately large detonation power. Therefore, the detonation waves
of the outside explosive 34 are instantaneously propagated around the
cord-like explosive members 30, and the detonation power of the outside
explosive 34 is applied simultaneously to the entire outer peripheral
portion of the inside explosive 20 in cross section perpendicular to the
center axis thereof. Thus, the detonation is triggered substantially at
the same time in all around the outer peripheral portion of the inside
explosive 20. As a result, the detonation power of the inside explosive
20 converges on the conventional munition 10.

[0048] Because the clearances are provided between the inside explosive 20
and the axial bottom surfaces both of the container 40, the detonation
waves of the outside explosive 34, when propagating radially outward on
the axial bottom surfaces both of the container 40, are not directly
transmitted to the inside explosive 20. This structural advantage helps
the detonation waves of the outside explosive 34 to be transmitted to the
inside explosive 20 from the outer peripheral surface thereof, thereby
focusing the detonation vector of the inside explosive 20 on the
conventional munition 10.

[0049] According to the blast treatment method described so far wherein
the outside explosive 34 having a larger detonation velocity is arranged
on the outer side of the inside explosive 20 so that the outside
explosive 34 initiates the detonation of the inside explosive 20, the
fragments of the conventional munition 10 can be prevented from
scattering outward.

[0050] Particularly, the method according to the present invention
initiates the detonation of the outside explosive 34 at the both ends
thereof in the axial direction of the container 40, in other words, in
the longitudinal direction of the conventional munition 10. As a result,
the detonation of the outside explosive 34 starts at the both ends
thereof at the same time, and the detonation of the inside explosive 20
then starts at the both ends thereof at the same time. The detonations of
the inside explosive 20 thus respectively started then are propagated so
as to approach each other along the longitudinal direction of the
conventional munition 10. Therefore, the detonations of the inside
explosive 20 are completed relatively promptly on the periphery of the
conventional munition 10, meaning that the detonations of the inside
explosive 20 are propagated in the longitudinal direction sooner than the
detonation of the bursting charge 12. As a result, the inward detonation
waves of the inside explosive 20 are propagated to the bursting charge
12, which ensures that the detonation vector of the bursting charge 12 is
directed inward.

[0051] Because the only detonator (initiation device) 50 is used to
initiate the detonation of the outside explosive 34 at the both ends
thereof, the outside explosive 34 can be easily initiated at the both
ends simultaneously.

[0052] The plurality of cord-like explosive members 30 including the
outside explosive 34 and having such a shape that unidirectionally
extends are arranged on the outer side of the inside explosive 20.
Therefore, the outside explosive 34 can be easily arranged suitably for
any shape of the conventional munition 10. The cord-like explosive
members 30 are arranged in parallel with the longitudinal direction of
the conventional munition 10 so that the detonation of the outside
explosive 34 and the detonation of the inside explosive 20 induced by the
detonation of the outside explosive 34 are both propagated in parallel
with the longitudinal direction. Therefore, completion of the detonation
of the inside explosive 20 is accelerated as compared to, for example, a
structure where the cord-like explosive members 30 are arranged in a
spiral shape on the outer peripheral surface of the inside explosive 20.

[0053] The cord-like explosive members 30 arranged around the inside
explosive 20 are equally spaced from one another so that the outside
explosive 34 included in the cord-like explosive members 30 equally
initiates the outer peripheral portion of the inside explosive 20.
Therefore, the outside explosive 34 used to initiate the inside explosive
20 can be reduced.

[0054] Though it is illustrated in the present exemplary embodiment that
the both ends of the outside explosive 34 in the longitudinal direction
of the conventional munition 10 are initiated, the sections of the
outside explosive 34 where the detonation is initiated is not necessarily
limited thereto as far as the outside explosive 34 is initiated at a
plurality of positions spaced from each other in a predefined direction.
As illustrated in FIG. 6, for example, the outside explosive 34 may be
initiated in vicinity of the center portion thereof in the longitudinal
direction of the conventional munition 10 as well as the both ends
thereof in the longitudinal direction of the conventional munition 10.

[0055] The present exemplary embodiment uses the 16 cord-like explosive
members 30 in which the detonating cord contains the outside explosive 34
(PETN) as its powder core, and the powder core is covered with the
external cylinder 32 made of plastic. However, the number of the
cord-like explosive members 30 and the types of the outside explosive 34
and the external cylinder 32 are not necessarily limited thereto.
Further, the cord-like explosive members 30 per se may not be necessarily
structured as described. Other examples of the cord-like explosive
members 30 are; composition C-4 formed in the shape of a cord, and a
sheet of explosive member formed in the shape of a tape in which an
explosive such as PETN is mixed. In place of using the cord-like
explosive members 30, a sheet of explosive member in which an explosive
such as PETN is mixed, for example, may be provided on the outer side of
inside explosive 20.

[0056] According to the present exemplary embodiment, the outside
explosive 34 is not provided at the axial center portion of the container
40, however, the outside explosive 34 may be provided on the whole outer
circumference of the inside explosive 20. As illustrated in FIG. 6, the
interior of the container 40 may be completely filled with the inside
explosive 20 without any clearance between the both ends of the inside
explosive 20 and the axial bottom surfaces both of the container 40.

[0057] The inside explosive 20 is not necessarily limited to the examples
given above. However, the emulsion explosive is relatively inexpensive
and has a greater detonation velocity than the ANFO explosive, thereby
more speedily propagating the detonation. Therefore, the emulsion
explosive helps to more efficiently blast the subject, while succeeding
in cost reduction of the whole blasting operation.

[0058] The container 40 according to the present exemplary embodiment has
a cylindrical shape, however, the shape of the container 40 is not
necessarily limited thereto. In place of using the container 40, an
explosive having plasticity may be used as the inside explosive 20. In
the case where such an inside explosive is used, the inside explosive 20
is securely provided around the conventional munition 10, and the
cord-like explosive members 30 are directly arranged on the outer
periphery of the inside explosive 20. The inside explosive 20 may be put
in a plurality of bags so that the plurality of bags laden with the
inside explosive 20 are mounted on the outer periphery of the
conventional munition 10, in which case the outside explosive 34 is
arranged around the bags. Another possible structure is to house the
conventional munition 10 and the inside explosive 20 alone in the
container 40 and then provide the outside explosive 34 on the outer side
of the container 40.

[0059] The treatment subject by the blast treatment method is not
necessarily limited to the conventional munition 10. The blast treatment
method can be applied to chemical bombs laden with explosives such as
TNT, picric acid, and RDX, blister agents such as mustard and lewisite,
sneezing agents such as DC and DA, and chemical agents such as phosgene,
sarin, and hydrocyanic acid. The blast treatment device 1 can also be
used to blast a unit containing the bursting charge after the
conventional munition 10 is disassembled.

[0060] As described so far, the present invention provides a blast
treatment method for blasting a treatment subject having a bursting
charge and a shell for housing therein the bursting charge, the method
comprising: an inside explosive disposing step of disposing an inside
explosive to be used to initiate detonation of the bursting charge and to
blast the treatment subject around the treatment subject; an outside
explosive disposing step of disposing an outside explosive having a
greater detonation velocity than the inside explosive and used to
initiate detonation of the inside explosive at positions on an outer side
of the inside explosive; and a blast step of simultaneously initiating
detonation of the outside explosive at a plurality of positions spaced
from each other at predetermined intervals along a particular direction
to thereby simultaneously initiate detonation of the inside explosive at
a plurality of positions along the particular direction by the detonation
of the outside explosive so that detonation of the bursting charge is
initiated by the detonations of the inside explosive, and thereby
blasting the treatment subject in such a manner that the detonations of
the inside explosive are completed before the detonation of the bursting
charge initiated by the detonations of the inside explosive is completed.

[0061] According to the method, the outside explosive having a greater
detonation velocity is disposed on the outer side of the inside explosive
so that the inside explosive is initiated by the outside explosive. Of
the detonation waves of the outside explosive, the detonation waves
directed inward are propagated to the inside explosive so that the
detonation vector of the inside explosive is directed inward. When the
inward detonation vector of the inside explosive is propagated to the
treatment subject, the detonation vector of the bursting charge loaded in
the treatment subject is directed inward. As a result, the fragments of
the treatment subject are prevented from scattering outward.

[0062] According to the blast treatment method, the outside explosive is
initiated simultaneously at the plurality of positions spaced from one
another at given intervals along the particular direction so that the
detonation of the inside explosive is thereby simultaneously initiated at
the plurality of positions in the particular direction. Therefore, the
detonations of the inside explosive are completed before the detonation
of the bursting charge initiated by the detonations of the inside
explosive is completed. Then, the detonation vector of the inside
explosive is more reliably propagated to the bursting charge, which
further ensures that the detonation vector of the bursting charge is
directed inward.

[0063] As far as the detonation of the inside explosive starts
simultaneously at the plurality of positions, the detonations of the
inside explosive end all over the outer side of the treatment subject
before the detonation propagation of the bursting charge overtakes the
detonation propagation of the inside explosive. This further ensures that
the inward detonation vector of the inside explosive is propagated to the
bursting charge not yet detonated, and the detonation vector of the
bursting charge thereby directed inward more reliably prevents the
fragments of the treatment subject from scattering outward.

[0064] According to the present invention, it is preferable that in the
blast step, both ends of the outside explosive in the particular
direction are simultaneously initiated to thereby simultaneously start
the detonation of the inside explosive at both ends thereof in the
particular direction by the detonation of the outside explosive, and
thereby propagating the detonations of the inside explosive which
respectively have started on the both ends thereof in the particular
direction so that the detonations approach each other along the
particular direction.

[0065] According to the method wherein the inside explosive is initiated
at one end of the inside explosive in the particular direction which is a
detonation start position and at the other end of the inside explosive
which is another detonation start point most distant from the one end in
the particular direction, the detonations of the inside explosive come to
an end in substantially half the time it takes for the detonation of the
inside explosive which started at one end thereof alone in the particular
direction to end. Therefore, before the detonation of the inside
explosive which started at the other end is propagated to the one end
before the detonation of the bursting charge which started at one end in
the particular direction overtakes the detonation of the inside
explosive. This further ensures that the detonation vector of the inside
explosive propagated to the bursting charge is directed inward, thereby
more reliably preventing the fragments of the treatment subject from
scattering outward.

[0066] The treatment subject has such a shape that extends in a given
direction. In the case where the bursting charge is initiated on one end
thereof alone in the longitudinal direction, the detonation propagation
of the bursting charge may overtake the detonation propagation of the
inside explosive. However, as far as the both ends of the outside
explosive in the longitudinal direction of the treatment subject are
initiated at the same time in the blast step to simultaneously start the
detonation of the inside explosive on the both ends thereof, completion
of the inside explosive detonation is accelerated.

[0067] According to the present invention, it is preferable that the
outside explosive disposing step includes a step of arranging a plurality
of cord-like explosive members, including the outside explosive and
having a shape that extends in a direction, at positions on the outer
side of the inside explosive in parallel with the particular direction,
and in the blast step, the detonation of the outside explosive included
in the plurality of cord-like explosive members is initiated at the both
ends in the particular direction.

[0068] According to the method, the cord-like explosive members formed so
as to extend in one direction are arranged on the outer side of the
inside explosive so that the outside explosive is arranged on the outer
side of the inside explosive. Therefore, when the cord-like explosive
members are differently arranged or shaped, a broad range of treatment
subjects can be suitably handled regardless of their different sizes and
shapes. Thus, the same cord-like explosive members can be used to blast
any subjects having various sizes and shapes, which makes it unnecessary
to prepare beforehand explosive members formed in shapes suitable for the
shapes of the different treatment subjects in order to arrange the
outside explosive on the outer side of the inside explosive. This
improves the efficiency of the blasting operation, thereby succeeding in
cost reduction.

[0069] According to the method wherein the cord-like explosive members are
arranged in parallel with the particular direction, the detonations of
the outside explosive included in the cord-like explosive members and the
detonations of the inside explosive triggered by the detonation of the
outside explosive are propagated in parallel with the particular
direction. Therefore, the detonations of the inside explosive which
progress along the particular direction come to an end sooner. This
further ensures that the detonation vector of the inside explosive
propagated to the bursting charge is directed inward, thereby more
reliably preventing the fragments of the treatment subject from
scattering outward.

[0070] The outside explosive disposing step preferably includes a step of
arranging the plurality of cord-like explosive members on an outer
periphery of the inside explosive to be equally spaced from each other.

[0071] As a result of the additional step, the outside explosive included
in the cord-like explosive members equally initiates the outer peripheral
portion of the inside explosive. This reduces the volume of the outside
explosive used to initiate the inside explosive.

[0072] The blast step preferably includes a step of propagating the
detonations of the outside explosive simultaneously initiated on the both
ends thereof in the particular direction so as to approach each other
along the particular direction, and thereby making the detonations of the
outside explosive crash into each other at a position on the outer side
of the inside explosive near a center portion of the inside explosive in
the particular direction.

[0073] The additional step makes the detonation waves of the outside
explosive crash into each other, thereby generating a high-pressure gas
having a large energy at the center portion in the particular direction.
The high-pressure gas thus generated prevents the fragments of the
treatment subject from scattering outward at the center portion in the
particular direction.

[0074] The outside explosive disposing step particularly includes a step
of arranging the outside explosive at any positions on the outer side of
the inside explosive except the center portion of the inside explosive in
the particular direction. The blast step preferably includes a step of
making the detonations of the outside explosive crash into each other in
a region where the outside explosive is not provided after propagating
the detonations so as to approach each other in the particular direction.

[0075] These additional steps arrange the outside explosive at any
positions of the inside explosive but the center portion thereof in the
particular direction while preventing the fragments of the treatment
subject from scattering outward using the high-pressure gas, thereby
reducing the volume of the outside explosive to be used for cost
reduction.

[0076] The both ends of the outside explosive in the particular direction
are preferably connected to a common initiation device so that the both
ends of the outside explosive are simultaneously initiated by the common
initiation device in the blast step.

[0077] Then, the both ends of the outside explosive can be more easily
initiated at the same time.

[0078] The present invention further provides a blast treatment device,
including: an inside explosive disposed on an outer side of a treatment
subject and used to blast the treatment subject; an outside explosive
having a greater detonation velocity than the inside explosive; and a
initiation device to be used to initiate detonation of the outside
explosive, wherein the initiation device is connected to the outside
explosive so that the outside explosive is initiated at a plurality of
positions spaced from each other at predetermined intervals along a
particular direction, the plurality of positions being such that
detonations of the inside explosive detonated by the detonations of the
outside explosive are completed earlier than the detonation of the
bursting charge detonated by the detonations of the inside explosive.

[0079] The device wherein the initiation device initiates the outside
explosive at the plurality of positions can more speedily complete the
inside explosive detonation so that the inward detonation vector of the
inside explosive is more reliably propagated to the bursting charge. This
inward detonation vector of the inside explosive more reliably prevents
the fragments of the object, such as a shell, from scattering outward.

[0080] The common initiation device of the blast treatment device is
preferably connected to both ends of the outside explosive in the
particular direction.

[0081] When the initiation device of the blast treatment device is thus
connected to the both ends, the initiation device initiates the both ends
of the outside explosive in the particular direction, thereby initiating
the detonations of the inside explosive and the bursting charge on both
ends thereof. As a result, the detonations of the inside explosive come
to an end before the detonation propagation of the bursting charge
overtakes the detonation propagation of the inside explosive. This
further ensures that the inward detonation vector of the inside explosive
is propagated to the bursting charge.